Memory trace dependence on number of stimuli in magnetic mismatch negativity

Mismatch negativity (MMN) reflects a comparison process between a deviant stimulus and the memory trace of standard stimuli. Although this memory mechanism has been investigated by many research studies, the development of memory representation still remains unclear. In this study, we focused on the development of sound trace underlying the MMN response. We measured the magnetic counterpart of MMN (MMNm) in detail, when the neural trace of the standard sound was developed in accordance with the number of standard stimuli. When the number of standard stimuli increased, MMNm latency significantly shortened and the MMNm amplitude showed no significant change. Thus, the developmental effects on memory trace may differ between MMNm amplitude and MMNm latency.